This invention relates to water-dispersible, biodegradable compositions of matter and to containers and the like made therefrom. More particularly, the invention relates to such compositions of matter which are resistant to fungal attack prior to dispersal and to containers and the like made therefrom.
Such containers are suitable for many diverse uses, for example, toilet-disposable catamenial tampon applicators, containers for patient laundry in a hospital, packets for addition of premeasured amounts of ingredients to aqueous fluids, and the like. Containers made from the composition of the invention are suitable for these uses because they are resistant to fungal attack prior to disposal in water or an aqueous solution, yet are biodegradable once disposed.
Water-dispersible compositions of matter are known which combine a water-insoluble, nonbiodegradable filler, such as talc, and a water-soluble, thermoplastic polymer, such as hydroxypropyl cellulose. Such compositions will disintegrate in an excess of water when the water-soluble polymer dissolves, leaving the water insoluble, nonbiodegradable filler dispersed therein. Hanke, U.S. Pat. No. 3,724,462, teaches that such filled compositions are superior to unfilled thermoplastic polymers in the manufacture of catamenial tampon applicators because they maintain their shape better under conditions of high humidity and temperature, are less likely to fuse together or adhere to the tampon under such conditions, and are much less expensive then unfilled thermoplastic polymers. A tampon applicator made according to the teaching of Hanke is toilet-disposable because of its water-dispersibility. The disadvantage with such compositions is, of course, that the filler is both insoluble and nonbiodegradable and hence accumulates wherever the composition is dispersed. Thus, if the composition is flushed in a water closet, the filler accumulates in the toilet or sewage system. Such a composition is also generally not suitable for the manufacture of containers designed for the addition of premeasured amounts of ingredients to aqueous fluids because the insoluble filler would accumulate therein, which is undesirable. Uses where the accumulation of such a nonbiodegradable filler would be disadvantageous are, for example, the addition of flavorings or colorings to food or the addition of soaps or detergents to laundry. The presence of, for example, talc in such as food or laundry is unacceptable.
The provision of a completely biodegradable, water-dispersible, filled composition has been an object which has so far eluded the art. Such a composition must be completely biodegradable after dispersal, yet must not be susceptible to attack by microorganisms, particularly fungi, prior to dispersal (e.g., while in storage). These apparently contradictory objects of long shelf life and ready biodegradability have not yet been achieved in a single filled composition.